Adsorption of carbon dioxide-methane mixtures in porous carbons: effect of surface chemistry

Abstract

A combined experimental and molecular simulation study of the coadsorption of CO 2 and CH 4 in porous carbons is reported. We address the effect of surface chemistry by considering a numerical model of disordered porous carbons which has been modified to include heterochemistry (with a chemical composition consistent with that of the experimental sample). We discuss how realistic the numerical sample is by comparing its pore size distribution, specific surface area, porous volume, and porosity with those for the experimental sample. We also discuss the different criteria used to estimate the latter properties from a geometrical analysis. We demonstrate the ability of the MP method to estimate pore size distribution of porous carbons from nitrogen adsorption isotherms. Both the experimental and simulated coadsorption isotherms resemble those obtained for pure gases (type I in the IUPAC classification). On the other hand, only the porous carbon including the heterogroups allows simulating quantitatively the selectivity of the experimental adsorbent for different carbon dioxide/methane mixtures. This result shows that taking into account the heterochemistry present in porous carbons is crucial to represent correctly adsorption selectivities in such hydrophobic samples. We also show that the adsorbed solution theory (AST) describes quantitatively the simulated and experimental coadsorption isotherms without any parameter adjustment.

Competitive adsorption of a binary CO2–CH4mixture in nanoporous carbons: effects of edge-functionalization

“…Fig. 4 shows the adsorption selectivity of CO 2 from an equimolar CO 2 /CH 4 mixture in edge-functionalized NPCs at low (0-5 MPa) and high (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) pressures at 298, 313, and 373 K. In Fig. 4, the selectivity of CO 2 over CH 4 in NPC is ~2, which is well consistent with that in the perfect graphite slit pore as reported by Wilcox 1 and that in mesoporous carbon as reported by Lu 48 .…”

Competitive adsorption of methane and carbon dioxide at nanometer level

“…[2]. The results show that the adsorption capacity of mixed gas coal is between that of pure CH 4 with that of CO 2 , and the adsorption of CH 4 and CO 2 mixed gas by coals show different characteristics; coal adsorbs CO 2 first, when pressure increases, the coal adsorbs more CO 2 and less CH 4 [3].…”

Triphasic Nature of Polymers of Intrinsic Microporosity Induces Storage and Catalysis Effects in Hydrogen and Oxygen Reactivity at Electrode Surfaces

“…1 nm) the definition of the terms such as “phase” and “gas bubble” need to be re‐considered as traditional phase boundaries may not be formed, even though a gas‐like mobile state may be retained. Examples of triphasic systems are known for metal‐organic frameworks, clays, zeolites, and porous carbons . The presence of the liquid sometimes serves to enhance the gas binding ability of the microporous material .…”

“…Examples of triphasic systems are known for metal-organic frameworks, [37] clays, [38] zeolites, [39] and porous carbons. [40] The presence of the liquid sometimes serves to enhance the gas binding ability of the microporous material. [41] Related hydrogen storage effects in porous organic hosts deposited onto platinum electrodes have also recently been noted to affect electrode processes.…”